Cereal-Based Product with Improved Eating Quality Fortified with Dietary Fiber and/or Calcium

ABSTRACT

Inhibition of expansion of a cereal product, such as a ready-to-eat cereal, by a particulate insoluble component such as fiber and/or calcium is avoided by pelletizing the particulate insoluble component. A binder component, such as gelatinized starch, is used to bind particles of the particulate insoluble component into a coherent mass which is formed into non-expanded pellets for fortification of the cereal product. The expanded cereal products, such as extruded puffed RTE cereals which contain the pellets, exhibit a crisp, uniform texture and cell structure, improved, prolonged bowl life, a non-gritty mouthfeel, and a smooth, uniform surface appearance even though they are fortified with high amounts of the solid or particulate insoluble nutritional components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application represents a divisional of application Ser. No.13/418,980 filed Mar. 13, 2012. The entire contents of which isincorporated herein.

FIELD OF THE INVENTION

The present invention relates to expanded cereal-based products withimproved eating quality which are fortified with particulate insolublecomponents such as dietary fiber and calcium, pellets for incorporationof the particulate insoluble component into an expanded cereal product,and methods for making the pellets and the expanded cereal-basedproducts.

BACKGROUND OF THE INVENTION

The expansion of ready-to-eat (RTE) breakfast cereals depends on anunimpeded expansion of the molten starch. Solid insoluble particles likedietary fiber or calcium carbonate interfere with the bubble formingprocess and thus hamper the extent and direction of the expansion whichadversely affect texture or mouthfeel, such as grittiness, surfaceappearance, and bowl-life of the finished cereal product. For example,the expansion of a twin screw extruded puffed cereal is reduced, producttexture is softened, bowl-life is reduced, gritty mouthfeel is created,and surface appearance becomes less smooth and uniform. Dealing with allof these effects is challenging because there are multipleinterconnected systemic parameters, such as viscosity and bubblenucleation, and mechanisms, such as rate of hydration and mechanicalmixing at work. When RTE cereals are fortified with both fiber andcalcium these challenges are further amplified.

U.S. Pat. No. 4,619,831 to Sharma discloses a dietary fiber compositionprepared by coating an insoluble fiber, such as enzymatically andchemically purified cereal bran, with a soluble fiber, such as ahydrocolloid, such as pectin or an alginate, where the amount ofinsoluble dietary fiber is about 92% to about 98.5% based on a dryweight basis of the total composition.

WO 99/65336 to Clark et al discloses agglomerated granules having agranule size of 88 to 2000 microns which when added to an ediblecomposition, substantially do not alter its sensory characteristics,where each agglomerated granule consists of agglomerated particles of afortificant such as calcium carbonate and a binder which is preferablycorn syrup.

WO 00/74501 to Hessel et al discloses wheat bran coated with psyllium,which is coated with pectin, which is coated with insoluble alginate,which is coated with glucose.

U.S. Pat. No. 7,981,453 to Chen et al discloses bran, cellulose, starch,a glucan, or a hydrocolloid in an amount of 45-75% by weight, which iscoated with a lipid in an amount of from 10-35% by weight, which iscoated with a protein in an amount of from 10-40% by weight.

Starch has been employed for the encapsulation of neutraceuticals, suchas vitamins, minerals, fatty acids, and probiotics to prevent theiroxidation and for controlled release. These formulations generallyemploy large amounts of starch for the encapsulation of the readilyoxidizable materials, which reduces the amount of the neutraceuticalavailable for incorporation into a foodstuff.

International Patent Publication No. WO 95/26752 (published Oct. 12,1995) discloses the production of a food product for the enteric supplyof a fatty acid, a fatty acid containing substance, an amino acid, or anamino acid containing substance by at least partially complexing thefatty acid or amino acid in the amylose helix of starch to mask theacid. The product may contain one or more flavors and colors, fatsoluble substances, anti-oxidants, or pharmacologically effectivesubstances. The components may be first dry mixed and subsequently fedinto an extruder where they are substantially mixed and subsequentlyheated above the gelatinization temperature of the starch to obtain anelasticized mass which is extruded and formed into pellets.

The production of expanded products is disclosed in European patentpublication nos. EP 0465364 A1 (published Jan. 8, 1992) and EP 0462012A2 (published Dec. 18, 1991), U.S. Pat. No. 3,962,416 to Katzen and U.S.Pat. No. 3,786,123 to Katzen. The two European patent publicationsdisclose the production of an anti-obesity food and a method for makingit by extrusion of starches with fatty acids into an expanded producthaving densities between 0.1 and 0.3 g/cm³. U.S. Pat. No. 3,962,416 toKatzen discloses an expanded product which contains at least onenutrient and one gelatinized starch. U.S. Pat. No. 3,786,123 to Katzendiscloses a method for producing encapsulated nutrients using extrusiontemperatures of between 250° F. and 400° F. and extrusion pressures ofbetween 200 psi to 2500 psi. A high protein encapsulating agentcontaining up to 40% starch may be used. The starch is gelatinized andextruded into an expanded product.

International Patent Publication No. WO 92/00130 (published Jan. 9,1992) discloses a continuous process for obtaining an encapsulated,biologically active product in a starchy matrix. A biologically activeagent and starch are mixed before extrusion and extruded as a blend,with the encapsulant or biologically active agent being heated togetherwith the starch. Alternatively, a core material to be encapsulated maybe added and blended with an aqueous dispersion of starch after thestarch and water have been subjected to an elevated temperaturesufficient to gelatinize the starch. The extrusion process, it isdisclosed, exposes the mix to high shear mechanical action at atemperature above the gelatinization temperature of the starch.

U.S. Pat. No. 5,183,690 to Carr, et al. discloses a continuous processfor imparting predetermined release properties to an encapsulatedbiologically active agent in a matrix of starchy material. The starchymaterial, an active agent, and water are continuously blended in aningredient stream wherein the starchy material is at a solidsconcentration of at least 40%. The ingredients stream is continuouslyextruded as an extrudate and the extrudate is continuously recovered.The conditions of blending, extruding, and recovering are preselected toyield the predetermined release properties.

U.S. Pat. No. 6,190,591 and International Publication No. WO 98/18610,published on May 7, 1998, both to Bernhard H. van Lengerich, disclose acontrolled release particulate composition which contains a hydrophobiccomponent for controlling the release of an encapsulated and/or embeddedactive component from a plasticized matrix. The controlled release ordelayed release composition may be produced without substantialexpansion of the matrix material to thereby avoid production of a lowdensity product which prematurely or too rapidly releases theencapsulant or the embedded component.

International Publication No. WO 00/21504 published on Apr. 20, 2000,U.S. Pat. No. 6,500,463 to Van Lengerich, and International PublicationNo. WO 01/25414 published on Apr. 12, 2001, disclose a continuousprocess for producing shelf-stable, controlled release, discrete, solidparticles from a liquid encapsulant component which contains a sensitiveencapsulant, such as a heat sensitive or readily oxidizablepharmaceutically, biologically, or nutritionally active component, suchas essential and/or highly unsaturated fatty acids. A liquid encapsulantcomponent which contains an active, sensitive encapsulant, such as alive microorganism or an enzyme dissolved or dispersed in a liquidplasticizer is admixed with a plasticizable matrix material. The matrixmaterial is plasticizable by the liquid plasticizer and theencapsulation of the active encapsulant is accomplished at a lowtemperature and under low shear conditions.

The present invention provides a method and product for incorporation ofa particulate insoluble component, such as dietary fiber and calcium,into an expanded cereal product, without substantial inhibition ofexpansion of the cereal product by the particulate insoluble component.Solid insoluble particles such as dietary fiber or calcium arepelletized so that they do not interfere with the bubble forming processand do not hamper the extent and direction of the expansion whichadversely affect texture or mouthfeel, such as grittiness, surfaceappearance, and bowl-life of the finished cereal product. Expandedcereal products, such as extruded puffed RTE cereals, produced inaccordance with the present invention are fortified with high amounts ofsolid or particulate insoluble nutritional components such as dietaryfiber and calcium but exhibit a crisp, uniform texture and cellstructure, improved, prolonged bowl life, non-gritty mouthfeel, and asmooth, uniform surface appearance. The pelletized neutraceuticalproducts contain relatively low amounts of starch or other materialsemployed for encapsulation of neutraceuticals which increases the amountof the insoluble nutritional component available for fortification of orincorporation into expanded RTE cereal products.

SUMMARY OF THE INVENTION

In accordance with the present invention, a pellet for incorporation ofa particulate insoluble component into an expanded cereal productcomprises particles of an insoluble component, such as fiber and/orcalcium, bound together by a binder component which binds the particlesof the insoluble component into a coherent mass to avoid inhibition ofexpansion of the cereal product by the particulate insoluble component.The binder component may be one or more of a partially gelatinizedstarch, or fully gelatinized starch. The degree of gelatinization of thestarch employed in the binder component provides sufficient binding tobind the particles of the particulate insoluble component, such asfiber, into a pellet, and may generally be at least about 25%,preferably at least about 75%, most preferably at least about 90% starchgelatinization, as measured by differential scanning calorimetry (DSC).The amount of binder component may be from about 5% by weight to about40% by weight, preferably from about 10% by weight to about 25% byweight, most preferably from about 15% by weight to about 20% by weight,based upon the total dry weight of the particulate insoluble componentand the binder component. The amount of the insoluble component may befrom about 60% by weight to about 95% by weight, preferably from about75% by weight to about 90% by weight, most preferably from about 80% byweight to about 85% by weight, based upon the total dry weight of theparticulate insoluble component and the binder component. The pellet mayhave a particle size of from about 200 μm to about 2 mm, preferably fromabout 500 μm to about 1.5 mm, most preferably from about 800 μm to about1200 μm. The total amount of the insoluble component and the bindercomponent may be at least about 75% by weight of the pellet, preferably,at least about 90% by weight, up to 100% by weight, based upon theweight of the pellet. The pellet may optionally contain at least oneadditive in an amount of up to about 25% by weight of the pellet. Thebinder component may comprise a gelatinized starch in an amount of atleast about 50% by weight, preferably at least about 75% by weight, morepreferably at least about 90% by weight, up to 100% by weight, basedupon the weight of the binder component, and an optional additionalbinder or binding agent in an amount of up to about 50% by weight, basedupon the weight of the binder component.

In an aspect of the invention, a cereal product comprises pieces ofexpanded ready-to-eat cereal and the pellets of the present inventionwhich are distributed substantially uniformly throughout the pieces ofexpanded ready-to-eat cereal. The expanded cereal pieces have a cellstructure comprising cell walls which form voids, and the pellets arepartially or completely contained in the cell walls or attached to thecell walls.

In an another aspect of the invention, the pellets for incorporation ofa particulate insoluble component, such as fiber and/or calcium, into anexpanded cereal product and to avoid inhibition of expansion of theexpanded cereal product by the particulate insoluble component, may beproduced by first forming a pellet dough. The dough may be produced byadmixing a particulate insoluble component, water, and a bindercomponent in an extruder to bind the particles of the particulateinsoluble component into a coherent substantially homogeneous mass,without substantial alteration of the native structure of the insolublecomponent such as the native structure of fiber. The dough may beextruded through a die to obtain an extrudate rope, the extrudate ropemay be cut into pieces, and the pieces may be dried to obtain pellets.The particulate insoluble component which is added to the extruder mayhave a particle size of at least about 200 μm, for example at leastabout 300 μm, but less than about half the diameter of the extrusion dieor extrudate rope. The extrusion may be conducted so as to avoidexpansion of the dough or extrudate of insoluble component and bindercomponent as it exits from the die, for example, at a temperature of themass at the extruder exit of less than 100° C. and a pressure of lessthan about 150 bars. The binder component may be a gelatinized starchwhich is produced by partially or fully gelatinizing a raw, or nativestarch, or ungelatinized starch in the extruder, or it may be apre-gelatinized starch which is added to the extruder and thenplasticized within the extruder by the water.

In another aspect of the invention, an expanded cereal product, such asa ready-to-eat cereal, which is fortified with a particulate insolublecomponent, such as fiber and/or calcium, may be produced by admixing atleast one flour, water, and the pellets of the present invention in anextruder to form a substantially homogeneous dough, extruding the doughthrough an extruder die to expand the dough, and cutting the expandeddough into pieces to obtain an expanded ready-to-eat cereal wherein aplurality of the pellets are distributed substantially uniformlythroughout the pieces of expanded ready-to-eat cereal. The expandedcereal pieces have a cell structure comprising cell walls which formvoids, and the pellets are partially or completely contained in the cellwalls or attached to the cell walls. The amount of the pellets may befrom about 5% by weight to about 50% by weight, preferably from about10% by weight to about 30% by weight, most preferably from about 15% byweight to about 25% by weight, based upon the total weight of the finalproduct, such as a ready-to-eat cereal. The expanded cereal products,such as extruded puffed RTE cereals, produced in accordance with thepresent invention are fortified with high amounts of solid orparticulate insoluble nutritional components, such as dietary fiber andcalcium. Even though large amounts of the insoluble components such asfiber and/or calcium are incorporated into the expanded RTE cereal, thecereal exhibits a crisp, uniform texture and cell structure, improved,prolonged bowl life, non-gritty mouthfeel, and a smooth, uniform surfaceappearance. The extent and direction of the expansion is essentiallyunhampered by the incorporation of the insoluble components, and is thesame or substantially the same as for products which do not contain theinsoluble components.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further illustrated by the accompanyingdrawings wherein:

FIG. 1 is a graph showing variation of pellet hardness as a function ofpellet composition for different ratios of wheat fiber and wheat bran.

FIG. 2A is a photograph showing fiber pellets in an expanded wheat flourextrudate (stained wheat fiber pellets, wheat fiber WF 600, Vitacell)

FIG. 2B is a photomicrograph showing a portion of the extrudate of FIG.2A where the fiber pellet is incorporated into the cell wall structureof the extrudate.

FIG. 3 shows the influence of pellet disintegration on the expansionproperties of an extruded, expanded breakfast cereal in terms of cellstructure, sectional expansion (SEI) and longitudinal expansion (LEI)using different ratios of pelletized and unpelletized wheat fibers.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have found that the combination of a particulateinsoluble component, such as fiber and/or calcium, and a bindercomponent, such as gelatinized starch, to bind the particles of theinsoluble component into a coherent mass which is formed intonon-expanded pellets avoids inhibition of expansion of a cereal product,such as a ready-to-eat cereal, by the particulate insoluble component.The expanded cereal products, such as extruded puffed RTE cereals,exhibit a crisp, uniform texture and cell structure, improved, prolongedbowl life, a non-gritty mouthfeel, and a smooth, uniform surfaceappearance even though they are fortified with high amounts of the solidor particulate insoluble nutritional components. The pelletizedneutraceutical products contain relatively low amounts of thegelatinized starch or other binding agents which increases the amount ofthe insoluble nutritional component available for fortification of orincorporation into expanded RTE cereal products.

The particulate insoluble component which is incorporated into thecereal product may be one or more of any particulate insoluble foodingredient, neutraceutical, or nutritional ingredient which wouldotherwise inhibit expansion of a ready-to eat cereal. As used herein theparticulate insoluble component includes any material which is at least40% by weight, for example at least 60% by weight, or essentiallycompletely insoluble in water at room temperature. Exemplary ofparticulate insoluble components are fiber and dietary minerals, such asa calcium, zinc, magnesium, iron, phosphorous, iodine, manganese,copper, selenium, molybdenum, sulfur, cobalt, nickel, chromium,fluorine, boron, and strontium salts, and mixtures thereof. Exemplary ofparticulate insoluble components which are dietary minerals which may beemployed in the present invention are calcium carbonate, calciumoxalate, calcium citrate, calcium phosphate, such as tricalciumphosphate, zinc carbonate, zinc oxide, and mixtures thereof.

The fiber may be any particulate insoluble fiber from any source,including sources of dietary fiber which contain both insoluble fiberand soluble fiber. As used herein, total dietary fiber (“TDF”) comprisesboth soluble dietary fiber (“SDF”) and insoluble dietary fiber (“IDF”).As used herein “dietary fiber” includes soluble and insoluble componentsof plant cell walls that are not digested by endogenous (non-bacterial)enzymes of a human digestive tract. Dietary fiber is not absorbed in thesmall intestine and thus enters the large intestine (colon). “Insolublefiber” includes oligo- and polysaccharides such as cellulose andhemicellulose. “Soluble fiber” is used to denote fiber that is at least50% soluble according to the method described by L. Prosky et al., J.Assoc. Off. Anal. Chem., 71, 1017-1023 (1988). Examples of soluble fiberinclude pectin, beta-glucans (small cellulose-type branched glucosepolymers), and gums such as xanthan gum. Uses of fiber additives infoods are reported as dietary fiber under the Nutrition Labeling andEducation Act (NLEA) of 1990.

Exemplary of sources of insoluble fiber which may be employed in thepresent invention are whole wheat, oat, corn, barley, rye, rice, andespecially in the bran of these cereals, fruits (such as apple, citrus,prune, mango, fig, etc.), vegetables (such as tomato, carrot, celery,etc.) or cocoa, resistant starch, and mixtures thereof. Preferredparticulate insoluble components which are fibers for use in the presentinvention include wheat bran, wheat fiber, corn bran, oat hull fiber,pea hull fiber, soy hull fiber, soy cotyledon fiber, sugar beet fiber,rice fiber, barley fiber, rye fiber, resistant starch, sugar cane fiber,sorghum fiber, vegetable fiber, fruit fiber, microcrystalline cellulose,and mixtures thereof.

In embodiments of the invention, combinations of fiber, such as wheatbran, and dietary minerals, such as calcium carbonate may be employed.

Commercially available particulate insoluble components, such as branand dietary minerals may be employed. They may be in powdered form inthe case of dietary minerals or may be in milled or ground form in thecase of fibers. In embodiments of the invention, the particulateinsoluble component may have a particle size of at least about 200 μm,for example at least about 300 μm, but generally less than about halfthe diameter of the extrusion die or extrudate rope, or pellet, or up toabout 1 mm.

The binder component employed in the present invention binds or gluesthe particles of the particulate insoluble component so that they sticktogether and form a coherent mass, which greatly reduces the surfacearea of the particulate insoluble component, and avoids inhibition ofexpansion of the cereal product by the particulate insoluble component.The binder component employed in the present invention includes agelatinized starch alone or in combination with one or more additionalbinding agents. The gelatinized starch may be partially gelatinized orfully gelatinized. The degree of gelatinization of the starch employedin the binder component provides sufficient binding to bind theparticles of the particulate insoluble component, such as fiber, into apellet, and may generally be at least about 25%, preferably at leastabout 75%, most preferably at least about 90% starch gelatinization, asmeasured by differential scanning calorimetry (DSC). The gelatinizedstarch is preferably produced by gelatinizing a raw or native starchin-situ during the pelletization of the particulate insoluble component.In other embodiments, a pregelatinized starch or modified starch may beemployed which can be plasticized by a liquid plasticizer such as waterduring the production of the pellets to obtain a plasticized mass whichbinds the particles of the particulate insoluble component.

Exemplary of raw or native starches which may be employed to obtain theat least partially gelatinized starch or modified or pregelatinizedstarch of the binder component include starches derived from corn,wheat, rice, potato, tapioca, or high amylose starch, and mixturesthereof. Sources of starch which may be used also include whole grain orrefined flours from grains such as corn, wheat, durum wheat, rice,barley, oats, rye, and mixtures thereof.

Examples of optional one or more binding agents which may be used withthe at least partially gelatinized starch include hydrocolloids such ascarrageenans, alginates, xanthan gum, gum arabic, guar flour or guargum, agar, tragacanth, karaya, locust bean gum, and pectin, solublefiber such as fructo-oligosaccharides, inulin, galacto-oligosaccharides,xylo-oligosaccharides, manno-oligosaccharides, polydextrose, resistantdextrins, cyclo-dextrins, acacia gum, larch gum, galactomannans such aslocust bean gum, tara gum, fenugreek, glucomannans or konjac flour,psyllium, high-methoxy pectins, beta-glucans from oat or barley,arabinoxylans from wheat, and chemically modified cellulosics, convertedstarches, dextrins, maltodextrins, glucose syrups, sugars, such as mono-and di-saccharides, wheat gluten, such as vital wheat gluten or isolatedgluten, vegetable or dairy proteins such as protein from soy or milk.The additional binding agents, such as maltodextrins, mono- ordi-saccharides may be used to affect disaggregation and adherence forincreasing the adherence between insoluble particulates and/or to aidthe functionality and properties of the gelatinized starch binder.

The amount of the at least partially gelatinized starch employed may beat least about 50% by weight, preferably at least about 75% by weight,more preferably at least about 90% by weight, up to 100% by weight,based upon the weight of the binder component. The amount of theoptional additional binder or binding agent may be up to about 50% byweight, for example up to about 25% by weight, generally up to about 10%by weight, based upon the weight of the binder component.

The amount of binder component may be from about 5% by weight to about40% by weight, preferably from about 10% by weight to about 25% byweight, most preferably from about 15% by weight to about 20% by weight,based upon the total dry weight of the particulate insoluble componentand the binder component. The amount of the insoluble component may befrom about 60% by weight to about 95% by weight, preferably from about75% by weight to about 90% by weight, most preferably from about 80% byweight to about 85% by weight, based upon the total dry weight of theparticulate insoluble component and the binder component.

The total amount of the insoluble component and the binder component maybe at least about 75% by weight of the pellet, preferably, at leastabout 90% by weight, up to 100% by weight, based upon the weight of thepellet. The pellet may optionally contain at least one additive in anamount of up to about 25% by weight of the pellet.

Exemplary of the one or more additives which may be employed in thepellets are glycerol, polyethylene glycol, sorbitol, fats or oils, andother softeners for manipulating or controlling the softness of thepellet. In embodiments of the invention, the pellets may be gluten-freefor use in the production of gluten-free cereal products.

The pellet may have a particle size of from about 200 μm to about 2 mm,preferably from about 500 μm to about 1.5 mm, most preferably from about800 μm to about 1200 μm.

The pellets of the present invention may be produced by forming a doughby admixing a particulate insoluble component, water, and a bindercomponent in an extruder to bind the particles of the particulateinsoluble component into a coherent mass, without substantial alterationof the native structure of the insoluble component such as the nativestructure of fiber. When the binder component includes more than onebinder or binding agent, they may be added as a substantiallyhomogeneous dry preblend, or separately added to the extruder andadmixed therein. In embodiments of the invention, when more than oneparticulate insoluble component is employed, they may be added as apreblend or separately added to the extruder. Also, the particulateinsoluble component and the binder component may be added as asubstantially homogeneous dry preblend or separately added to theextruder.

The amount of water employed should be sufficient to form an extrudablehomogeneous dough or plasticized mass. Exemplary amounts of water whichmay be used are from about 10% by weight to about 50% by weight,generally from about 20% by weight to about 40% by weight, based uponthe total weight of the dough.

The extrusion may be conducted so as to avoid expansion of the dough orextrudate of insoluble component and binder component as it exits fromthe die. For example, the extrusion may be conducted so that thetemperature of the mass at the extruder exit is less than 100° C. andthe extruder pressure is less than about 150 bars. When the bindercomponent is a gelatinized starch which is produced by gelatinizing araw, or native starch, or ungelatinized starch in the extruder, theextrusion temperature should be above the gelatinization temperature ofthe starch. Extrusion temperatures below the gelatinization temperatureof starch, such as room temperature, may be employed when the bindercomponent is a pre-gelatinized starch which is added to the extruder andthen plasticized within the extruder by the water. The dough may beextruded through a die to obtain an extrudate rope, the extrudate ropemay be cut into pieces, and the pieces may be dried to obtain pellets.

In embodiments of the invention, a dough comprising all ingredients maybe made using a conventional batch mixer and a conventional continuousmixer with subsequent extrusion using a single screw extruder. In otherembodiments of the invention, the dough can be made continuously using acontinuous mixer or extruder alone. Twin screw extruders or co-rotatingtwin screw mixers may be advantageously used which enable the steps ofcontinuously mixing the dough and subsequently extruding the doughthrough an extrusion die plate. Co-rotating intermeshing twin screwextruders, such as those available from Buhler, Switzerland, ClextralFrance, Werner and Pfleiderer Germany, APV England or Wenger USA, or aCo-Kneader, available from Buss, Switzerland may be employed.

For feeding solid components to an extruder, conventional solids feedingdevices such as a volumetric or gravimetric feeder may be used. Liquidinjection nozzles may be used for injecting liquid components orsolutions, dispersions, emulsions or suspensions.

The admixing of the ingredients inside the extruder may be accomplishedby using an appropriate extrusion screw configuration for achieving lowshear mixing. For example, a combination of alternating small pitchconveying elements with distributive mixing elements, that are staggeredat an angle to each other for providing axially oriented leakage flowinside the extruder barrel may be employed. The combination ofalternating conveying elements with distributive mixing elements causethe material flow to be continuously interrupted without shearing of themass thus resulting in mixing of the material at low mechanical energyinput. In other embodiments of the invention, other extruder screwconfigurations may be used that facilitate low shear distributivemixing, such as screw elements of the type ZME, TME, SME, and so-calledIGEL elements commercially available from Werner and Pfleiderer.

The total length of the distributive mixing section may be about 3 to 12l/d, preferably about 4 to 6 l/d to sufficiently admix and distributethe binding component with the particulate insoluble component. The atleast substantially homogeneous mixture of plasticized binding componentand particulate insoluble component may then be conveyed towards anextruder die plate. The conveying may be achieved by the use of lowpitch extruder screw conveying elements which build up sufficientpressure prior to extruding the mix so that it can be forced through theapertures in the die plate. Another function of the low pitch elementsis that they increase the degree of fill inside the last extruder barrelsection. The increased degree of fill enables control of the temperatureprofile of the mix inside the extruder barrel for achieving optimumviscosity adjustment and extrusion through the subsequent die openings.The dough or crumbly mass or mix may be extruded, pressed or compressedthrough extrusion dies having aperture diameters of from about 0.1 mm toabout 2 mm, preferably from about 0.5 mm to about 1.5 mm. The diameterof the extrudate rope and product may be larger than the diameter of thedie apertures due to deformation or swelling as the composition exitsthe die. The increase in diameter upon exiting the die may occur with noor substantially no development of an expanded, puffed, foamy, orcellular structure. The extruded rope may have a cross-sectionaldiameter of from about 0.2 mm to about 2 mm, preferably from about 0.5mm to about 1.5 mm, most preferably from about 0.8 mm to about 1.2 mm.

The extrudate rope may be cut at the die face using a rotating cutter,pelletizer, or rotating knives. In other embodiments, the extrudate ropemay be cut away from the die using conventional cutting or forming meansfor producing pellets or tablets. The cut pieces or pellets, may have alength:diameter ratio (l/d ratio) of about 0.5 to 10, preferably about1.

After cutting, the resulting pieces or pellets may be dried to asufficiently low moisture content which assures a sufficiently prolongedstorage stability or shelf life. For example, the pellets may be driedto achieve a storage stability or shelf life of at least about sixmonths, preferably at least about twelve months, most preferably atleast about thirty-six months. In embodiments of the present invention,the drying may be performed using conventional drying equipment usingdrying temperatures which do not adversely affect the thermal stabilityof the components. Exemplary drying temperatures may range from about20° C. to about 90° C., generally from about 60° C. to about 85° C. Thedrying may be conducted to achieve a moisture content of less than about30% by weight, preferably less than about 12% by weight, most preferablyless than about 10% by weight, for example less than about 8% by weight.The product may be dried using a conventional fluidized bed or otherconventional drying means.

The pellets of the present invention may be used to fortify conventionalcereal product formulations, to produce fortified cereal products, suchas ready-to eat cereals, using conventional cereal processing equipmentand processes. For example, an expanded cereal product, such as aready-to-eat cereal, which is fortified with a particulate insolublecomponent, such as fiber and/or calcium, may be produced by admixing atleast one flour, water, and the pellets of the present invention in anextruder to form a dough in conventional manner. The flour may be anyflour conventionally employed in the production of cereal products suchas whole grain or refined flours from grains such as corn, wheat, durumwheat, rice, barley, oats, rye, and mixtures thereof.

The dough may be extruded through an extruder die to expand the dough,using conventional extrusion temperatures and pressures employed for theproduction of expanded ready-to-eat cereals or snacks. Exemplaryextrusion temperatures may range from about 100° C. to about 150° C.,generally from about 105° C. to about 135° C., and extrusion pressuresmay range from about 10 bar to about 100 bar, generally from about 25bar to about 75 bar. The expanded dough may be cut into pieces to obtainan expanded ready-to-eat cereal or snack. The expanded RTE cereal orsnack may have a plurality of the pellets distributed substantiallyuniformly throughout the pieces of expanded ready-to-eat cereal orsnack. The expanded cereal pieces have a cell structure comprising cellwalls which form voids, and the pellets are partially or completelycontained in the cell walls or attached to the cell walls. The pelletsmay be substantially unexpanded in the expanded cereal product. Duringthe extrusion and/or expansion process, the starch of the cereal productmay be melted to form a molten starch matrix without interference ordeleterious interaction with the particulate insoluble component such asfiber or calcium. The reduced contact area achieved by pelletizing theparticulate insoluble component, such as fiber or calcium, prior to theproduction of the expanded cereal product reduces or eliminates thenegative influence of the particulate insoluble component on the moltenstarch matrix and expansion process, such as the number of air cellsproduced, and the thickness of the cell walls in the expanded product.

The amount of the pellets may be from about 5% by weight to about 50% byweight, preferably from about 10% by weight to about 30% by weight, mostpreferably from about 15% by weight to about 25% by weight, based uponthe total weight of the final product, such as a ready-to-eat cereal orexpanded snack. The expanded cereal products, such as extruded puffedRTE cereals, produced in accordance with the present invention arefortified with high amounts of solid or particulate insolublenutritional components, such as dietary fiber and calcium. Even thoughlarge amounts of the insoluble components such as fiber and/or calciumare incorporated into the expanded RTE cereal, the cereal exhibits acrisp, uniform texture and cell structure, improved, prolonged bowllife, non-gritty mouthfeel, and a smooth, uniform surface appearance.The extent and direction of the expansion is essentially unhampered bythe incorporation of the insoluble components, and is the same orsubstantially the same as for products which do not contain theinsoluble components.

The present invention is further illustrated by the followingnon-limiting examples where all parts, percentages, proportions, andratios are by weight, all temperatures are in ° C., and all pressuresare atmospheric unless otherwise indicated:

EXAMPLE 1 Production of Fiber Pellets

A dry matrix blend consisting of 15 parts starch and 85 parts dietaryfiber was fed into a feed port of a Werner & Pfleiderer twin screwextruder at a rate of 4 kg/hr. Water was fed at a rate of 1.6 kg/hr intothe same barrel of the twin screw extruder. All barrels of the extruderwere kept at a temperature of 16° C. The die consisted of 40 circularopenings, each 1 mm in diameter. At a screw speed of 150 rpm, the aboveingredients were conveyed and formed into a dough that was extrudedthrough the die openings at a pressure of 100 bar and a producttemperature of 90° C. On a calculated basis, the rate of extrudate perdie area is 0.1783 kg/hr per mm². Upon exiting the die, the exitingropes were cut with rotating knives into discrete particles of 1 mmlength and dried in a convection oven until their moisture content wasbelow 5% wmb. The resulting pellets contain insoluble dietary fiberswhich were stuck together by plasticized starch particles.

EXAMPLE 2 Production of Fiber Pellets

Fiber pellets may be produced as in Example 1 except a dry matrix blendconsisting of 20 parts starch and 80 parts dietary fiber may beemployed.

EXAMPLE 3 Production of Fiber Pellets

Fiber pellets may be produced as in Example 1 except a dry matrix blendconsisting of 25 parts starch and 75 parts dietary fiber may beemployed.

EXAMPLE 4 Production of Fiber Pellets

Fiber pellets may be produced as in Examples 1 to 3 except wheat branmay be used as a source of part of the starch as well as the fibersource.

EXAMPLE 5 Production of Fiber Pellets of Varying Hardness

In the Example, the hardness of fiber pellets is altered by changingtheir fiber composition. Different dry matrix blends consisting of 15parts starch and 85 parts dietary fiber were prepared. The 85 parts ofdietary fiber consisted of wheat bran/wheat fiber mixtures. The mixtureswere changed by varying the ratio of wheat bran and wheat fiber in therange of (100:00, 75:25, 50:50, 25:75, 00:100). The prepared mixtureswere fed into a feed port of a Werner & Pfleiderer twin screw extruderat a rate of 4 kg/hr. Water was fed at a rate of 1.6 kg/hr into the samebarrel of the twin screw extruder. All barrels of the extruder were keptat a temperature of 16° C. The die consisted of 40 circular openings,each 1 mm in diameter. At a screw speed of 150 rpm, the aboveingredients were conveyed and formed into a dough that was extrudedthrough the die openings at a pressure of 90 bar and a producttemperature of 90° C. Upon exiting the die, the exiting ropes were cutwith rotating knives into discrete particles of 1 mm length and dried ina convection oven until their moisture content was below 5% wmb. Theresulting pellets contain insoluble dietary fibers which were stucktogether by plasticized starch particles. The pellets made fromdifferent wheat bran (WB)/wheat fiber (WF) compositions had differenthardnesses. The hardness was expressed as a maximum force (N) requiredfor a cut through the pellet, and the results are shown in FIG. 1 asranging from about 20N to about 145N, with hardness increasing as theproportion of wheat fiber increases and the portion wheat brandecreases.

EXAMPLE 6 Use of Dietary Fiber Pellets in Extruded Products

A dry matrix blend consisting of 90 parts wheat flour and 10 parts ofdietary fiber pellets as obtained in Example 1 was fed into a feed portof a Werner & Pfleiderer twin screw extruder at a rate of 7.38 kg/hr.Water was fed at a rate of 0.405 kg/hr into the same barrel of the twinscrew extruder. The first two barrel segments were kept at 16° C. Thebarrel segments 3, 4, 5, and 6 were heated to 110° C. The die consistedof 1 circular opening of 3 mm in diameter. At a screw speed of 275 rpm,the above ingredients were conveyed and formed into a dough that wasextruded through the die opening at a pressure of 50 bar and a producttemperature of 130° C. Upon exiting the die, the expanded exiting ropeswere collected on trays and dried in a convection oven at 80° C. for 1hr. The resulting products contained pelletized dietary fiber. The fiberpellets remained intact after the extrusion and were integrated into thecell walls of the expanded structure as shown in FIGS. 2A and 2B.

EXAMPLE 7 Influence of Pellet Disintegration on Expansion Properties

Five different matrix blends consisting of 95 parts wheat flour and 5parts of dietary fiber were prepared. The 5 parts of dietary fiber werechanged for each blend by using different ratios of pelletized andunpelletized wheat fibers. The prepared blends were fed into a feed portof a Werner & Pfleiderer twin screw extruder at a rate of 7.38 kg/hr.Water was fed at a rate of 0.405 kg/hr into the same barrel of the twinscrew extruder. The first two barrel segments were kept at 16° C. Thebarrel segments 3, 4, 5, and 6 were heated to 110° C. The die consistedof 1 circular opening of 3 mm in diameter. At a screw speed of 275 rpm,the above ingredients were conveyed and formed into a dough that wasextruded through the die opening at a pressure of 50 bar and a producttemperature of 130° C. Upon exiting the die, the expanded exiting ropeswere collected on trays and dried in a convection oven at 80° C. for 1hr. The resulting products contained pelletized dietary fiber with adifferent degree of disintegration (dod). As shown in FIG. 3, the higherthe degree of disintegration was, the higher was the negative influenceof fiber on the expansion and texture properties. The sectionalexpansion (SEI) decreased and the longitudinal expansion (LEI) increasedif the dod increased. The air cells in the product became smaller anddenser if the dod increased as shown in FIG. 3.

What is claimed is:
 1. A pellet for incorporation of a particulateinsoluble component into an expanded cereal product, said pelletcomprising particles of an insoluble component bound together by abinder component which binds the particles of the insoluble componentinto a coherent mass to avoid inhibition of expansion of the cerealproduct by the particulate insoluble component, the binder componentcomprising at least one member selected from the group consisting ofpartially gelatinized starches, and fully gelatinized starches, theamount of binder component being from about 5% by weight to about 40% byweight, and the amount of the insoluble component being from about 60%by weight to about 95% by weight, based upon the total dry weight of theparticulate insoluble component and the binder component, the pellethaving a particle size of from about 200 μm to about 2 mm.
 2. A pelletas claimed in claim 1 wherein the particulate insoluble componentcomprises at least one member selected from the group consisting offibers and calcium components.
 3. A pellet as claimed in claim 1 whereinthe particulate insoluble component comprises fiber.
 4. A pellet asclaimed in claim 3 wherein the fiber comprises at least one memberselected from the group consisting of wheat bran, wheat fiber, cornbran, oat hull fiber, pea hull fiber, soy hull fiber, soy cotyledonfiber, sugar beet fiber, rice fiber, barley fiber, rye fiber, resistantstarch, sugar cane fiber, sorghum fiber, vegetable fiber, fruit fiber,and microcrystalline cellulose, the total amount of the insolublecomponent and the binder component is at least about 75% by weight ofthe pellet, and the pellet contains at least one additive in an amountof up to about 25% by weight of the pellet.
 5. A pellet as claimed inclaim 1 wherein the particulate insoluble component comprises insolubledietary fiber.
 6. A pellet as claimed in claim 2 wherein the amount ofthe particulate insoluble component is from about 75% by weight to about90% by weight, and the amount of the binder component is from about 10%by weight to about 25% by weight, based upon the total dry weight of theparticulate insoluble component and the binder component, and the pellethas a particle size of from about 500 μm to about 1.5 mm.
 7. A pellet asclaimed in claim 2 wherein the amount of the particulate insolublecomponent is from about 80% by weight to about 85% by weight, and theamount of the binder component is from about 15% by weight to about 20%by weight, based upon the total dry weight of the particulate insolublecomponent and the binder component, and the pellet has a particle sizeof from about 800 μm to about 1200 μm.
 8. A pellet as claimed in claim 5wherein the amount of insoluble dietary fiber is from about 75% byweight to about 90% by weight, and the amount of the binder component isfrom about 10% by weight to about 25% by weight, based upon the totaldry weight of the particulate insoluble component and the bindercomponent, and the pellet has a particle size of from about 500 μm toabout 1.5 mm.
 9. A pellet as claimed in claim 1 wherein the bindercomponent comprises a gelatinized starch in an amount of at least about50% by weight, based upon the weight of the binder component, and anadditional binding agent in an amount of up to about 50% by weight,based upon the weight of the binder component, wherein the additionalbinding agent is at least one member selected from the group consistingof hydrocolloids, soluble fibers, proteins, converted starches,dextrins, maltodextrins, glucose syrups, and sugars.
 10. A pellet asclaimed in claim 8 wherein the binder component is a gelatinized starch.11. A pellet as claimed in claim 9 wherein the gelatinized starch is apregelatinized starch.
 12. A pellet as claimed in claim 1 wherein theparticulate insoluble component is at least one particulate fibercomponent selected from the group consisting of wheat bran, wheat fiber,corn bran, oat hull fiber, pea hull fiber, soy hull fiber, soy cotyledonfiber, sugar beet fiber, rice fiber, barley fiber, rye fiber, resistantstarch, sugar cane fiber, sorghum fiber, vegetable fiber, fruit fiber,and microcrystalline cellulose, the binder component is a gelatinizedstarch, the amount of the fiber component is from about 75% by weight toabout 90% by weight, and the amount of the binder component is fromabout 10% by weight to about 25% by weight, based upon the total dryweight of the fiber component and the gelatinized starch, and the pellethas a particle size of from about 500 μm to about 1.5 mm.
 13. A pelletas claimed in claim 1 which is gluten-free.
 14. Pellets forincorporation into an expanded cereal product, each said pelletcomprising a coherent mass from a mixture of a particulate insolublecomponent, water, and a binder component, with particles of theparticulate insoluble component bound into the coherent mass, cut andformed into dry pieces, the binder component including at least onemember selected from the group consisting of partially gelatinizedstarches and fully gelatinized starches, wherein the amount of bindercomponent is from about 5% by weight to about 40% by weight, and theamount of the insoluble component is from about 60% by weight to about95% by weight, based upon a total dry weight of the particulateinsoluble component and the binder component, and the pellets have aparticle size of from about 500 μm to about 1.5 mm.
 15. The pellets asclaimed in claim 14, wherein the particulate insoluble component of thepellets comprises at least one member selected from the group consistingof fibers and calcium components.
 16. The pellets as claimed in claim 15further comprising, in combination, pieces of an expanded ready-to-eatcereal, wherein the pellets are distributed substantially uniformlythroughout the pieces of the expanded ready-to-eat cereal, the expandedcereal pieces having a cell structure comprising cell walls which formvoids, the pellets are partially or completely contained in the cellwalls or attached to the cell walls, the amount of the pellets is fromabout 5% by weight to about 50% by weight, based upon the total weightof the ready-to-eat cereal.
 17. The pellets as claimed in claim 16,wherein the pellets are not expanded.
 18. The pellets as claimed inclaim 16, wherein the particulate insoluble component comprises at leastone particulate fiber component selected from the group consisting ofwheat bran, wheat fiber, corn bran, oat hull fiber, pea hull fiber, soyhull fiber, soy cotyledon fiber, sugar beet fiber, rice fiber, barleyfiber, rye fiber, resistant starch, sugar cane fiber, sorghum fiber,vegetable fiber, fruit fiber, and microcrystalline cellulose, the amountof the particulate insoluble component of the pellets is from about 75%by weight to about 90% by weight, and the amount of the binder componentis from about 10% by weight to about 25% by weight, based upon the totaldry weight of the particulate insoluble component and the bindercomponent, the pellets have a particle size of from about 500 μm toabout 1.5 mm, and the amount of the pellets is from about 5% by weightto about 50% by weight, based upon the total weight of expanded theready-to-eat cereal.
 19. A cereal product comprising: pieces of expandedready-to-eat cereal; and pellets including particles of an insolublecomponent bound together by a binder component which binds the particlesof the insoluble component into a coherent mass to avoid inhibition ofexpansion of the cereal product by the particulate insoluble component,the binder component comprising at least one member selected from thegroup consisting of partially gelatinized starches, and fullygelatinized starches, the amount of binder component being from about 5%by weight to about 40% by weight, and the amount of the insolublecomponent being from about 60% by weight to about 95% by weight, basedupon the total dry weight of the particulate insoluble component and thebinder component, the pellet having a particle size of from about 200 μmto about 2 mm, wherein a plurality of pellets are distributedsubstantially uniformly throughout the pieces of expanded ready-to-eatcereal, the expanded cereal pieces have a cell structure comprising cellwalls which form voids, and the pellets are partially or completelycontained in the cell walls or attached to the cell walls, theparticulate insoluble component of the pellets comprises at least onemember selected from the group consisting of fibers and calciumcomponents, and the binder component of the pellets comprises agelatinized starch in an amount of at least about 50% by weight, basedupon the weight of the binder component.
 20. A cereal product as claimedin claim 19 wherein the particulate insoluble component comprises atleast one particulate fiber component selected from the group consistingof wheat bran, wheat fiber, corn bran, oat hull fiber, pea hull fiber,soy hull fiber, soy cotyledon fiber, sugar beet fiber, rice fiber,barley fiber, rye fiber, resistant starch, sugar cane fiber, sorghumfiber, vegetable fiber, fruit fiber, and microcrystalline cellulose, theamount of the particulate insoluble component of the pellets is fromabout 75% by weight to about 90% by weight, and the amount of the bindercomponent is from about 10% by weight to about 25% by weight, based uponthe total dry weight of the particulate insoluble component and thebinder component, the pellets have a particle size of from about 500 μmto about 1.5 mm, and the amount of the pellets is from about 5% byweight to about 50% by weight, based upon the total weight of the cerealproduct.